JP2001-235013A discloses a hydraulic control device for vehicle automatic transmission that prevents a hydraulic lock in a signal pressure oil passage at a low temperature to improve responsiveness of a hydraulic control valve.
In JP2001-235013A, a hydraulic-lock-preventing oil passage is disposed. The hydraulic-lock-preventing oil passage drains a part of signal pressure to a signal pressure oil passage, which supplies signal pressure from a linear solenoid valve to a signal oil chamber in a hydraulic control valve. This ensures preventing the hydraulic lock and a quick communication between an output port and a drain port.